This proposal describes the design and testing of new enzyme-based amperometric sensors for glucose where the electrical communication between the flavin redox centers of glucose oxidase and an electrode is achieved via a network of donor-acceptor relays chemically bound to a highly flexible polymer. The sensors should have widespread technological applications in areas such as the clinical laboratory, veterinary health care, the research laboratory, and the food industry. Because the electrode, the development of a reusable in vitro blood glucose monitor (for self-monitoring by diabetic patients) appears feasible in the near future. The polymeric relay systems are also amenable to needle-type probes which could be useful for subcutaneous glucose monitoring. The proposed research plan for Phase II concerns the development of highly stable, sensitive and selective glucose sensors through a systematic study of new polymeric electron relay systems, new enzyme immobilization schemes, and new electrode configurations and materials.